re PR middle-end/27084 (Does not propagate memory load base through useless type conversion)

2006-07-05  Richard Guenther  <rguenther@suse.de>
	Andrew Pinski  <pinskia@gcc.gnu.org>

	PR c++/27084
	* cp-objcp-common.c (cxx_types_compatible_p): Ignore
	top level qualifiers for pointer type comparisons.

	* g++.dg/tree-ssa/copyprop-1.C: New testcase.

Co-Authored-By: Andrew Pinski <pinskia@gcc.gnu.org>

From-SVN: r115200

gcc/cp/ChangeLog

+2006-07-05  Richard Guenther  <rguenther@suse.de>
+	Andrew Pinski  <pinskia@gcc.gnu.org>
+
+	PR c++/27084
+	* cp-objcp-common.c (cxx_types_compatible_p): Ignore
+	top level qualifiers for pointer type comparisons.
+
 2006-07-01  Jason Merrill  <jason@redhat.com>
 
 	PR c++/28215

gcc/cp/cp-objcp-common.c

@@ -179,7 +179,8 @@ cxx_types_compatible_p (tree x, tree y)
   if (POINTER_TYPE_P (x) && POINTER_TYPE_P (y)
       && TYPE_MODE (x) == TYPE_MODE (y)
       && TYPE_REF_CAN_ALIAS_ALL (x) == TYPE_REF_CAN_ALIAS_ALL (y)
-      && same_type_p (TREE_TYPE (x), TREE_TYPE (y)))
+      && same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (x),
+						    TREE_TYPE (y)))
     return 1;
 
   return 0;

gcc/testsuite/ChangeLog

+2006-07-05  Richard Guenther  <rguenther@suse.de>
+	Andrew Pinski  <pinskia@gcc.gnu.org>
+
+	PR c++/27084
+	* g++.dg/tree-ssa/copyprop-1.C: New testcase.
+
 2006-07-04  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/28174

gcc/testsuite/g++.dg/tree-ssa/copyprop-1.C

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-dce2" } */
+
+/* Verify that we can eliminate the useless conversions to/from
+   const qualified pointer types
+     this_2 = o_1;
+     D.20003_4 = this_2->data_m;
+     this_5 = D.20003_4;
+     D.20005_6 = this_5->value;
+   copyprop should propagate o_1 and D.20003_4 to the loads of data_m
+   and value.  dce removes all traces of this.  */
+
+struct Data {
+  int get() const { return value; }
+  int value;
+};
+
+struct Object {
+  int operator[](int i) const { return data_m->get(); }
+  Data *data_m;
+};
+
+int foo(Object&o)
+{
+  return o[0];
+}
+
+/* { dg-final { scan-tree-dump-not ".* = \[^>;\]*;" "dce2" } } */
+/* { dg-final { cleanup-tree-dump "dce2" } } */